In the world of sweet corn, a fascinating interplay between beneficial and harmful fungi is unfolding. According to Agricultural Research Service (ARS) scientists, the very defenses that help some sweet corn varieties resist fungal diseases can also hinder the effectiveness of a beneficial fungus used to combat destructive caterpillar pests. This intricate relationship highlights the need for a nuanced approach to managing these complex interactions, especially for organic growers with limited options for disease and insect control.
The Dent Corn Conundrum
Previous research by the team on field (dent) corn, grown largely for livestock feed and other applications, was intriguing. Pathogen-induced resistance to the biopesticide Beauveria bassiana could reduce control of insect pests such as European corn borer and fall armyworm larvae in some Fusarium-resistant lines of dent corn.
Since not all the Fusarium-resistant dent corn lines did exhibit a loss of Beauveria insecticidal activity, it can also be speculated that either the gene for resistance to F. proliferatum is tightly linked to a gene responsible for altering synthesis or secretion of toxin in Beauveria or too few strains were investigated to properly address an apparent mechanism underlying the apparent diminished toxicity of a given strain when confronted with Dent-42 versus W64A maize roots. Another finding was that certain lines were resistant to letinase feeding, indicating an allelic association where good genes for fighting cowpea rust variety of fungi and potentially avoiding unfavorable can be found alongside favorable genes to aid colonisation of beneficial (mycorrhiza by the Vesicular—Arbuscular Fungus) symbionts.
The Sweet Corn Conundrum
The scientists next studied sugar-enhanced sweet corn as a model for development. They compared different lines of Fusarium-resistant hybrid or inbred sweet corn and found that the effectiveness of the Beauveria biopesticide was contingent upon sweet corn line, with similar rates among amphotericin B and difenoconazole.
Fusarium Disease In sweet corn lines that showed even better disease resistance, as shown by smaller spots of leaf death caused by the fungus Fusarium (left), caterpillar mortality from Beauveria was higher. In contrast, in other sweet corn types with less resistance, the ability of caterpillar control was lower when the larger dead spots were greater
Sweet corn variety appeared to influence the efficacy of Beauveria, though the impact varied depending on the strain of fungus evaluated; thus further research is needed for improved practical guidance to aid growers with sweet corn selection in their integrated pest management systems.
Discovering Organic is Still the Sweet Spot
Simpson said this balance between Fusarium resistance and Beauveria compatibility is important, especially for organic growers with fewer options to control disease and insects. It would be a revolution for these farmers if they could find the right combination of these traits in sweet corn varieties.
Recent gene expression studies on sweet corn that compared hybrids with differing Fusarium resistance and Beauveria efficacy have also been very informative according to Drs. The results will also help in selecting Sweet Corn varieties that exhibit high levels of insecticidal activity using Beauveria and the ones displaying resistance to Fusarium.
As the researchers decode the machinations of this elaborate dance between fungi, they say their work will allow organic growers to plant sweet corn varieties that can succeed in outsmarting both fungal diseases and caterpillars trying to snack on them.
